Migration Scenarios

Now that we have discussed the new concepts and issues with Windows NT Directory Services, we can work through the migration of the traditional Windows NT domain model to the Next-generation model. The difference between the Windows NT4 domain models model is the number of domains involved and the trusts between them. The migration process is grown through the different scenarios.

Windows NT 4.x and earlier support several domain models, distinguished by the number of domains and the trust relationships between the domains. Four domain models are described in the planning guide for earlier versions of Windows NT:

• Single Domain Model. All users and resources are contained in a single domain, and there are no trust relationships.
• Master Domain Model. Users are contained in a single domain and resources are contained in one or more "second tier" domains, also known as "resource domains." Resource domains trust the master domain.
• Multiple-master Domain Model. A variation on the master domain model, in which users are contained in two or more master domains, which trust each other, and resources are contained in resource domains. As in the master domain model, the resource domains trust all the master domains.
• Complete Trust Model. A model in which users and resources are spread across two or more domains, all of which trust each other.

All of these models (and the variations on them) can be easily migrated to the next generation Directory Service. The migration process is divided into two parts:

Upgrading the Domain

Forming the Tree

These steps are performed the same way regardless of the domain model(s) in use. The only difference is the number of times each step needs to be performed. In the case of Resource domains, you have the option of (a) keeping the resource domain after migrating it or (b) folding the resource domain into one of the former "master" domains and using delegation of authority in the container hierarchy to provide the desired granularity of administrative responsibility.